控轧控冷对Ti-Mo-Nb复合微合金化低碳钢组织和力学性能的影响

研究了控轧控冷的冷却速度对Ti-Mo-Nb微合金高强钢组织与性能的影响。结果表明，随着冷却速度的降低，试验钢中铁素体逐渐等轴化，铁素体的体积分数、晶粒尺寸逐渐增加。冷却速度的降低可显著细化析出相尺寸并增加其体积分数，析出方式由弥散析出向相间析出转变。铁素体通过析出强化实现提升材料强度的同时，成形性能得到改善。当冷却速度为28℃/s时，试验钢获得了优异的综合力学性能，抗拉强度为853 MPa,屈服强度为750 MPa,伸长率为18.6%,扩孔率为68.5%。组织细化与析出强化是试验钢的主要强化机制，当冷却速度为28℃/s时，细晶强化和析出强化强度增量分别为206 MPa和328 MPa。

Effect of TMCP on microstructure and mechanical properties of Ti-Mo-Nb microalloyed low carbon steel

Effect of cooling rate of TMCP on microstructure and mechanical properties of Ti-Mo-Nb microalloyed steel was studied. The results show that as the cooling rate decreases, the ferrite grains become equiaxed and the volume fraction and grain size of the ferrite gradually increase. Reducing the cooling rate can significantly refine the size of the precipitates and increase its volume fraction, and the precipitation behavior changes from dispersive precipitation to interphase precipitation. The precipitation strengthening of ferrite improves the strength of the tested steel, as well as the formability. When the cooling rate is 28 ℃/s, an excellent combination of strength and ductility is obtained as the tensile strength of 853 MPa, the yield strength of 750 MPa, the elongation of 18.6%and the hole expansion rate of 68.5%. The grain refinement strengthening and precipitation strengthening are the main strengthening mechanisms of the tested steel, when the cooling rate is 28 ℃/s, the strength increments of grain refinement strengthening and precipitation strengthening are 206 MPa and 328 MPa, respectively.